How to Fix My Network Problems with Xbox Live?

Everytime i play modern warfare 2 it disconnects me from xbox live around every 2 hours. Then it will disconnect and disconnect around 4-5 times. I've open ports on my router *i know i have them correctly done* I have tried to manually put in the network settings through the network configuration..I dont it all. I searched google and found nothing I havn't all ready done. I'm sick and tired of it and I need some help.

Suggestion:

You need a new modem. I had same problem. Modem fixed it right up.